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Posts: 383
| Repowered my 681 this week with a new 115 Etec. Love the motor so far and I'm glad i did it. Now, on to props...Saved my 19 pitch Raker from my old Faststrike. While I'm getting a darn good hole shot, top end isn't there yet. Any suggestions? Thanks. |
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Posts: 477
Location: Iowa | If you are low on wide open throttle rpm's, you should try to find a 21 pitch to try. Otherwise might want to try a different style prop. Steve usually had the most insight on this if he sees it. |
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Posts: 13688
Location: minocqua, wi. | i suggest you find VMS Steve and get a recommendation for the highest pitch Rev4 you can run on that hp motor. try a Rev4 before committing to a 3-blade, but make sure you have the highest pitch you can turn successfully. the lift you get in the back and the overall range of the ride is pretty darn good. i would imagine the 681 will respond similarly to what we've found in the 690's or the same vintage. |
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Posts: 477
Location: Iowa | jonnysled - 7/14/2012 9:31 AM
i suggest you find VMS Steve and get a recommendation for the highest pitch Rev4 you can run on that hp motor. try a Rev4 before committing to a 3-blade, but make sure you have the highest pitch you can turn successfully. the lift you get in the back and the overall range of the ride is pretty darn good. i would imagine the 681 will respond similarly to what we've found in the 690's or the same vintage.
What he said! I had a 681vs with a 125 on it, wish I would have messed with props on it a little. Knowing what I do now, I think I would have been pleasantly surprised. |
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Posts: 3504
Location: Elk River, Minnesota | Hiya,
First and foremost, a big thank you to many of you..you are all way to kind.
O.k... onto the Etec. If hole shot was really good but top end not there, that would be a first indicator of not having enough pitch on the prop, or the prop itself is not able to lift the bow as well as a 4 blade could.
I believe the 681 has it's gas tank toward the front? If that is the case, a high rake prop like the raker is a good choice in a 3 blade, but in many of the cases of the 690 series of rangers, a good 4 blade prop with good cup on the tips and trailing edge have been key. For your motor, a Rev4 may not fit unless the rev4 has the option of exchangeable hubs....and it very well might. Another good option would be the OMC renegade.
The best thing you can do before purchasing would be to find a dealer that has a demo prop program (blue props) and see if they have a few different models to try out in different pitches. Then, head to the lake and test test test....one will stick out as a best performer and the boat will just feel like it will float along at cruising speed, yet handle well in both low end and top end.
Do you happen to know what kind of RPM's you were seeing at full throttle with the Raker and the max RPM's the etec can take? I'm guessing the etec is somewhere around 6000 for max.
With the 115 on the 681, I would think you are probably looking at a 40 mph boat..maybe a touch more.
I'll help if I can.
Steve
Edited by VMS 7/14/2012 1:12 PM
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Posts: 383
| Thanks, all, for the good info. A couple things I should have mentioned. First, my Raker is an 18 (apparently, Rakers were only made in even pitches).
Also, while I have a good hole shot, I'm having difficulty getting to, much less above 5000 rpm at WOT. According to the charts, I should be at 5500-6000.
The good news is that the dealership is good about lending out props to try. Test time!
Edited by hooked 7/14/2012 1:01 PM
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Posts: 3504
Location: Elk River, Minnesota | Hiya,
The decent hole shot is due to the prop being vented, which is a very nice feature.
If you are having trouble getting to 5000, you are over pitched by about 4 inches. When propping the motor, the best thing you can do to get overall performance under different loads is to load your boat lightly and get a prop on it that takes you to 6000 rpms.
The unfortunate part of that, though...I don't think they make a raker in a 14 pitch.
If you can find a good ballistic propeller, you might be able to get a 15 pitch to work as they run about the same rpm as a stock aluminum (at least in my experience with them) Better yet with that motor on a 681, a good 4 blade ballistic or even a solas amita 4 might do well. Lots to try...
Steve |
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Posts: 383
| The first prop the dealer leant was a Viper 17. Sounds like it still might be too much? Won't get it on the water til tomorrow... |
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Posts: 3504
Location: Elk River, Minnesota | I think so... Worth a try though...
Steve |
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Posts: 433
Location: Cedarburg, Wisconsin | Hooked, before you mess with props, make sure your motor is mounted high enough to get the cavitation plate out of the water when you run WOT and trimmed up. If you are plowing water with too much of the gearcase the results will be not what you want. Been there and done that with my E-TEC when I first got it. Total waste of time swapping props (tried 4) as the rpms changed and the speed stayed the same. Just trying to save you some aggravation. Also prop to hit that rpm range with your boat loaded, not running light.
Vipers, like Laser II's are for lighter go fast boats, probably not what you want on a fishing rig. I'd second the Rev 4 if it'll fit. Stay away from Cyclone props, way too hard to turn as they don't have vent holes. The Renegades have a smaller diameter and even with the ring they are easy to blow out with an E-TEC. The Raker isn't a bad prop but I think there are better out there.
Edited by Almost-B-Good 7/15/2012 5:46 AM
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Posts: 383
| Thanks for the heads-up on the Cyclone, as I was thinking that would be the next choice. I'll see how it goes today with the Viper and if that doesn't work, I'll check into the Rev tomorrow. I'll keep an eye on how the motor's riding today too. Thanks to all for the help!
Edited by hooked 7/15/2012 8:05 AM
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Posts: 383
| Well, tried the Viper out... Just to 5500 at WOT... Low 40s on the GPS (though due to boat traffic I never got any real long runs at WOT). Still a good hole shot and on plane fast... ???? |
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